Nuclear Theory·nucl-th

Tuesday·February 2, 2021

14 papers—8 primary·6 cross-listed

09
[Submitted on 29 Jan 2021] (cross-list from hep-ph)
The mass radius of the proton
Dmitri E. Kharzeev🇺🇸
The mass radius is a fundamental property of the proton that so far has not been determined from experiment. Here we show that the mass radius of the proton can be rigorously defined through the formfactor of the trace of the energy-momentum tensor (EMT) of QCD in the weak gravitational field approximation, as appropriate for this problem. We then demonstrate that the scale anomaly of QCD enables the extraction of the formfactor of the trace of the EMT from the data on threshold photoproduction of $J / ψ$ and $Υ$ quarkonia, and use the recent GlueX Collaboration data to extract the r.m.s. mass radius of the proton $R_{m} = 0.55 \pm 0.03 fm$ . The extracted mass radius is significantly smaller than the charge radius of the proton $R_{C} = 0.8409 \pm 0.0004 fm$ . We attribute this difference to the interplay of asymptotic freedom and spontaneous breaking of chiral symmetry in QCD, and outline future measurements needed to determine the mass radius more precisely.
Comments:
20 pages, 3 figures; 2 typos fixed
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2102.00110 [pdf]
PRD(2021)·143 citations
10
[Submitted on 30 Jan 2021] (cross-list from hep-lat)
Dibaryon with highest charm number near unitarity from lattice QCD
Yan Lyu🇨🇳 · Hui Tong🇨🇳 · Takuya Sugiura🇯🇵 · Sinya Aoki🇯🇵 · Takumi Doi🇯🇵 · Tetsuo Hatsuda🇯🇵 · Jie Meng🇨🇳 · Takaya Miyamoto🇯🇵
A pair of triply charmed baryons, $Ω_{ccc} Ω_{ccc}$ , is studied as an ideal dibaryon system by (2+1)-flavor lattice QCD with nearly physical light-quark masses and the relativistic heavy quark action with the physical charm quark mass. The spatial baryon-baryon correlation is related to their scattering parameters on the basis of the HAL QCD method. The $Ω_{ccc} Ω_{ccc}$ in the $^{1} S_{0}$ channel taking into account the Coulomb repulsion with the charge form factor of $Ω_{ccc}$ leads to the scattering length $a_{0}^{C} ≃ - 19 fm$ and the effective range $r_{eff}^{C} ≃ 0.45 fm$ . The ratio $r_{eff}^{C} / a_{0}^{C} ≃ - 0.024$ , whose magnitude is considerably smaller than that of the dineutron ( $- 0.149$ ), indicates that $Ω_{ccc} Ω_{ccc}$ is located in the unitary regime.
Comments:
6 pages, 4 figures; Supplemental Material(1 page, 1 figure); Accepted for publication in Physical Review Letters
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2102.00181 [pdf]
PRL(2021)·94 citations
11
[Submitted on 31 Jan 2021] (cross-list from physics.atom-ph)
Nuclear polarization effects in atoms and ions
V.V. Flambaum🇦🇺 · I.B. Samsonov🇦🇺 · H.B. Tran Tan🇦🇺 · A.V. Viatkina🇩🇪
In heavy atoms and ions, nuclear structure effects are significantly enhanced due to the overlap of the electron wave functions with the nucleus. This overlap rapidly increases with the nuclear charge $Z$ . We study the energy level shifts induced by the electric dipole and electric quadrupole nuclear polarization effects in atoms and ions with $Z \geq 20$ . The electric dipole polarization effect is enhanced by the nuclear giant dipole resonance. The electric quadrupole polarization effect is enhanced because the electrons in a heavy atom or ion move faster than the rotation of the deformed nucleus, thus experiencing significant corrections to the conventional approximation in which they `see' an averaged nuclear charge density. The electric nuclear polarization effects are computed numerically for $1 s$ , $2 s$ , $2 p_{1/2}$ and high $n s$ electrons. The results are fitted with elementary functions of nuclear parameters (nuclear charge, mass number, nuclear radius and deformation). We construct an effective potential which models the energy level shifts due to nuclear polarization. This effective potential, when added to the nuclear Coulomb interaction, may be used to find energy level shifts in multi-electron ions, atoms and molecules. The fitting functions and effective potentials of the nuclear polarization effects are important for the studies of isotope shifts and nonlinearity in the King plot which are now used to search for new interactions and particles.
Comments:
17 pages, 3 figures, 10 tables
Subjects:
Atomic Physics (physics.atom-ph); Nuclear Theory (nucl-th)
arXiv:
2102.00355 [pdf]
PRA(2021)·15 citations
12
[Submitted on 1 Feb 2021] (cross-list from hep-ph)
Neutrino-nucleon DIS from Holographic QCD: PDFs of sea and valence quarks, form factors, and structure functions of the proton
Kiminad A. Mamo🇺🇸 · Ismail Zahed🇺🇸
We discuss unpolarized neutrino- and anti-neutrino-nucleon deep inelastic scattering (DIS) using a chiral doublet of baryonic sources with explicit symmetry breaking, in a slice of AdS $_{5}$ with both a hard and soft wall. We explicitly derive the direct and transition form factors for the vector and axial-vector currents for the holographic dual of a proton and neutron. We use them to derive the s-channel structure functions for neutrino and anti-neutrino scattering on a proton and neutron in bulk. The t-channel contributions stemming from the Pomeron and Reggeon exchanges are also evaluated explicitly. The pertinent even and odd structure functions in the limit of large and small parton momentum fraction $x$ are given. The results allow for the extraction of the nonperterbative parton distribution functions carried by the sea and valence quarks both at large-x and small-x regimes. Our holographic PDF sets compare well with LHAPDF and CTEQ PDF sets in the large-x and small-x regimes in the intermediate range of $Q^{2} < 10 Ge V^{2}$ .
Comments:
54 pages, 10 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2102.00608 [pdf]
PRD(2021)·8 citations
13
[Submitted on 1 Feb 2021] (cross-list from hep-ph)
The $Λ (1405)$ in resummed chiral effective field theory
X.-L. Ren🇩🇪 · E. Epelbaum🇩🇪 · J. Gegelia🇩🇪 · Ulf-G. Meißner🇩🇪
We study the unitarized meson-baryon scattering amplitude at leading order in the strangeness $S = - 1$ sector using time-ordered perturbation theory for a manifestly Lorentz-invariant formulation of chiral effective field theory. By solving the coupled-channel integral equations with the full off-shell dependence of the effective potential and applying subtractive renormalization, we analyze the renormalized scattering amplitudes and obtain the two-pole structure of the $Λ (1405)$ resonance. We also point out the necessity of including higher-order terms.
Comments:
16 pages, 3 figures, 5 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2102.00914 [pdf]
EPJC(2021)·11 citations
14
[Submitted on 1 Feb 2021] (cross-list from astro-ph.HE)
Maximum mass of compact stars from gravitational wave events with finite-temperature equations of state
Sanika Khadkikar🇮🇳 · Adriana R. Raduta🇷🇴 · Micaela Oertel🇫🇷 · Armen Sedrakian🇩🇪
We conjecture and verify a set of universal relations between global parameters of hot and fast-rotating compact stars, including a relation connecting the masses of the mass-shedding (Kepler) and static configurations. We apply these relations to the GW170817 event by adopting the scenario in which a hypermassive compact star remnant formed in a merger evolves into a supramassive compact star that collapses into a black hole once the stability line for such stars is crossed. We deduce an upper limit on the maximum mass of static, cold neutron stars $2.1 5_{- 0.07}^{+ 0.10} \leq M_{TOV}^{⋆} \leq 2.2 4_{- 0.10}^{+ 0.12}$ for the typical range of entropy per baryon $2 \leq S / A \leq 3$ and electron fraction $Y_{e} = 0.1$ characterizing the hot hypermassive star. Our result implies that accounting for the finite temperature of the merger remnant relaxes previously derived constraints on the value of the maximum mass of a cold, static compact star.
Comments:
17 pages, 11 figures
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2102.00988 [pdf]
PRC(2021)·65 citations

Affiliations

first authorsco-authorsvia INSPIRE

The mass radius of the proton

Dibaryon with highest charm number near unitarity from lattice QCD

Nuclear polarization effects in atoms and ions

Neutrino-nucleon DIS from Holographic QCD: PDFs of sea and valence quarks, form factors, and structure functions of the proton

The Λ(1405) in resummed chiral effective field theory

Maximum mass of compact stars from gravitational wave events with finite-temperature equations of state

Affiliations

The $Λ (1405)$ in resummed chiral effective field theory